Japanese stars create incredible piece of tennis history at US Open

"She does a really good job. of holding the baseline and redirecting the ball", Keys said. Keys ability to hit winners even from deep in the court is one of her most impressive attributes and one that Osaka will need to be wary of.

She dropped only seven points on her serve playing on Arthur Ashe Stadium and needed just 57 minutes to rip through Tsurenko.

American Madison Keys clinched her second consecutive U.S. Open semi-final berth on Wednesday, using her powerful serve and fiery forehand to get an edge on 30th seed Carla Suarez Navarro and win 6-4 6-3.

Nishikori raced into a 4-1 lead but Cilic broke back to take the set to 4-4.

Nishikori then reeled in Marin Cilic to win in five sets. "I used to play here when I was a little kid, so these courts aren't new to me", Osaka said.

As Osaka has climbed the ranks in women's tennis, her identity has been the subject of curiosity for many tennis fans. That was at Wimbledon in 1995, and both Shuzo Matsuoka and Kimiko Date lost in that round. "I wasn't nervous before the match, but as soon as I got into the court, it was different".

The crisis soon deepened for Tsurenko, who had needed the best part of three hours on Monday to beat Czech teenager Marketa Vondrousova in a match where she nearly collapsed due to heat exhaustion.

That semi-final win a year ago, over Coco Vandeweghe, was her solitary Grand Slam semi-final victory, with her other two appearances at this stage resulting in defeats - albeit both times as underdog, to varying degrees - against Serena Williams and Sloane Stephens. "My entire body was shaking so I was really glad I was able to play well today".

"I didn't want to pull out as it's a Grand Slam quarter-final but she played well".

The match was a repeat of the 2014 US Open final, which Cilic won, and the Croatian made a strong start as he took the opening set.

Kei Nishikori is headed to the US Open semifinal following a dramatic upset victory over Marin Cilic on Wednesday.

That said, in KeysOsaka faces one of the few players capable of matching her blow for blow and not missing.

Tsurenko labored in the heat during her fourth-round victory over Marketa Vondrousova, having her temperature and blood checked during a medical timeout in the first set and almost quitting when she trailed early in the second.

"I think the guy's beat a brick wall once", Millman said, "because he makes you work hard for every point and it's relentless". Osaka put it best after her quarterfinal win: "Sometimes I go insane and then I start hitting everything".

This will be the pair's first meeting and it's hard to see anything but a straightforward win for the 23-time Slam champ. She recovered to win in three sets, with her opponent accusing her of acting after the match.